How Far Apart Should Iron Posts Be on a Stairwell Railing?

All open stairs more than 30 inches off the ground must have appropriate railings.

Iron stair railings lend a classic beauty to the home but, like all stair railings, can pose a serious safety risk when improperly installed. While codes once allowed you to space iron posts or balusters 6 inches apart, modern codes have reduced this spacing to help prevent accidents and injuries.

Stair Rail Spacing

According to the 2012 International Residential Code, iron posts on stairs must be placed close enough together so that a sphere measuring 4 3/8 inches in diameter is unable to pass through. This requirement is typically met by placing two posts on each stair. Any horizontal landings in the top, middle or bottom of the staircase require slightly different spacing. The posts on these horizontal landings must be placed close enough together so that a sphere measuring 4 inches in diameter is unable to pass through.

Building to Code

Information on stair rail spacing can be found in Section 312 of the International Residential Code. While the IRC is not a law in and of itself, it serves as the basis for building codes throughout most of the United States. Always refer to your local building code to confirm the exact requirements in your area when installing an iron stair rail.

About the Author

Emily Beach works in the commercial construction industry in Maryland. She received her LEED accreditation from the U.S. Green Building Council in 2008 and is in the process of working towards an Architectural Hardware Consultant certification from the Door and Hardware Institute. She received a bachelor's degree in economics and management from Goucher College in Towson, Maryland.